Bismuth iodide complex of salts of racemic 2-dehydroemetine



United States Patent and June 2, 1964, 9,118/63 1 Claim. (Cl. 260-270) The present invention relates to novel bismuth iodide organic complexes and to a process for preparing same. More particularly, the present invention relates to bismuth iodide complexes of Z-dehydroernetine and pharmaceutically acceptable salts thereof and to a process for the manufacture of such bismuth iodide complexes.

Z-dehydroemetine is 2-(6,7'-dimethoxy-l,2,3,4-tetrahydro l isoquinolylmethyl)-3-ethyl-9,lO-dimethoxy- 1,4,6,7-tetrahydro-l1bH-benzo[a] quinolizine. 2-dehydroemetine possesses two asymmetrical centers. Thus, there are possible 4-optical antipodes or Z-r-acemates thereof. The expression Z-dehydroernetine as used throughout the specification is intended to encompass all such forms thereof. Thus, it will accordingly be appreciated that the expression Z-dehydroemetine as used herein connotes the optical antipodes thereof, particularly, (-)-2- dehydroernetine as well as the racemates thereof.

The novel process aspect of the present invention involves the reaction of a bismuth iodide complex salt with a member selected from the group consisting of Z-dehydroemetine and acid addition salts thereof with pharmaceutically acceptable acids whereby to form the said new and useful bismuth iodide complex of Z-dehydroemetine.

Z-dehydroemetine is characterized by its amoebicidal activity and thus, is extremely useful in the control of amoebic dysentery. However, Z-dehydroemetine suffers from the defect of being unsuitable for oral administration due to the likelihood of undesirable side effects occurring when this substance is administered by this route.

The bismuth iodide complex of Z-dehydroemetine of the present invention, however, while being characterized by its ability to control amoebic dysentery and bilharziosis, can be administered orally without significant undesirable side effects occurring. Thus, it is unexpectedly superior to 2-dehydroemetine per se, insofar as its capability of being administered orally is concerned. The present invention therefor provides a novel class of pharmaceutically desirable products which are suitable for oral administration.

Among the acid addition salts of Z-dehydroemetine with pharmaceuti-cally acceptable acids suitable for use in the process of the present invention may be included salts thereof with weak organic acids such as aliphatic carboxylic acids, for example, formic acid, acetic acid, propionic acid, tartaric acid, oxalic acid, lactic acid and the like, and, salts with weak inorganic acids, e.g. the hydroiodic acid salt of Z-dehydroemetine and the like.

Salts of Z-dehydroemetine with strong acids can also be employed in the novel process aspect of the present invention. However, this procedure is less preferred since it may result in the end product containing undesired anionic impurities (chloride ions). However, such anionic impurities will not be present in sufficient quantities as to alfect the use of the end products for pharmaceutical purposes.

A preferred salt suitable for the use as a starting material in the process aspect of the present invention is the acetate salt of Z-dehydroemetine. Either the acetate salt per so can be provided for use in the preferred process aspect or a salt of Z-dehydroe-metine, for example, a Z-dehydroemetine hydrohali-de salt, can be neutralized to the free base, the so-for'med free base can be added to an 3,287,456 Patented Nov. 22, 1966 appropriate amount of acetic acid and the resultant acetic acid salt of Z-dehydroemetine can be reacted with the bismuth iodide inorganic complex salt whereby to form the desired complex.

Among the bismuth iodide complex salts suitable for the purposes of the present invention may be included any inorganic salt which contains the anion [Bil and which will form a bismuth iodide complex with Z-dehydroemetine or its pharmaceutically acceptable acid addition salts. Thus, alkali-metalbismuth iodides such as 'potassium bismuth iodide or.-ammonium bismuth iodide are suitable 'for the purposes of the present invention. If an alkali-metal bismuth iodide is employed in the process of the present invention, it can be prepared, in situ, ,from bismuth oxide (Bi Og) in any conveniently available alkali metal iodide such as potassium iodide.

The lbismuth iodide complexes of 2-dehydroemetine of the present invention have the empirical formula The bismuth iodide complexes of pharmaceutically acceptable acid addition salts of Z-dehydroemetine have the empirical formula C H O N -BiI -acid. The ratio of the Z-dehydroemetine moiety to the bismuth iodide moiety in the complex may vary within wide limits. However, preferably, there is complexed with every one part of the Z-de hydroemetine moiety of the empirical formula from about 0.7 to about 2.0 parts of the bismuth iodide moiety of empirical formula BiI Still more preferably, there is complexed with every 1 part of the 2-dehydro emetine moiety, from about 0.80 part to about 1.50 parts of the bismuth iodide moiety. The acid portion of the complex can similarly vary in the ratio of from about 0.7 to about 2.0 parts thereof for every one part of the 2-dehydroemetine moiety.

Thus, the novel product of the present invention is a bismuth iodide complex of a member selected fromt-he group consisting of Z-dehydroemetiue and acid addition salts thereof-with pharmaceutically acceptable acid, there being present in the complex for every 1 part of the dehydroemetine moiety from about 0.7 to about 2.0 parts of the Bil moiety. Advantageously, the product is a bismuth iodide complex of the hydroiodic salt of 2-dehydroemetine.

The complexes obtainable according to the process of the present invention are, as is noted above, useful as,

Example 1 25.0 grams of racemic Z-dehydroemetine dihydrochloride (moisture content 2.3 percent) and 40 grams of ice were suspended in 160 ml. of water. After the addition of 11 ml. of 30 percent sodium hydroxide solution, the reaction mixture was extracted 3 times with chloroform. Thee hloroform extracts were combined and evaporated. The residue which contains racemic 2- dehydroemetine as the free base was dissolved in ml. of glacial acetic acid. To the resultant solution, there was rapidly added at a temperature of about 25, a solution prepared by combining 103 ml. of saturated potassium iodide solution, 10.3 grams of bismuth-(III)- oxide and 255 ml. of glacial acetic acid. The resultant mixture was stirred for a period of one hour. An orangered precipitate which formed was separated by filtration, washed several times with water and then dried under reduced pressure at 45 The so-dried material was added with stirring to a solution of 50 ml. of ethanol in 50 ml. of water, and the stirring was continued after the addition was completed. After drying under reduced pressure, (12 mm. Hg) at 45, there was obtained the bismuth iodide complex of the hydroiodic acid salt of racemic-2-dehydroemetine as an orange-red powder of the following composition: C H O N .2HI.1.16BiI Example 2 The free base of racemic Z-dehydroemetine was prepared as in Example 1 from 100 grams of racemie 2- dehydroernetine dihydrochloride and then dissolved in 600 ml. of glacial acetic acid. To the resultant solution, there was added at a temperature of 40 with stirring, 900 ml. of a potassium bismuth iodide solution. After such addition was completed, the resultant mixture was stirred for a period of about 1 hour and then filtered. The vermillion residue remaining on the filter was washed portionwise with 300 ml. of water and then dried at 50 in a vacuum drying oven, yielding the bismuth iodide complex of the hydroiodic salt of racemic Z-dehydroemetine.

The product was made into a paste by adding the same to 500 ml. of 50 percent aqueous ethanol and stirring the resultant mixture for a period 1 hour at 40. The sostirred mixture was then filtered and dried to a constant weight in a vacuum drying oven at 50. The so-dried product-was-found to have the composition of The free base, (-)-2-dehydroemetine, obtained from 1 gram of (-)-2-dehydroemetine dihydrobromide as in Example 1, was dissolved in 5.2 ml. of glacial acetic acid.

To the resultant solution, there was added with stirring at about 40, 7.8 ml. of potassium bismuth iodide "solution, said last-mentioned solution having been prepared in the manner set forth in Example 2. The stirring was continued for a period of 1 hour. An orange-red precipitate which appeared was separated by filtration, Washed with water and dried. The powder obtained on drying was added to 4.3 ml. of a water-ethanol mixture (3: 1) and the resultant mixture was stirred for a period of 1 hour at 40. The resulting paste was filtered and dried yielding the bismuth iodide complex of (-)-2- dehydroemetine containing ()-2-dehydroemetine, B11 and H1 in a proportion of 1: 1.41:1.05.

Example 4 The active complex prepared by the procedure exemplified in Example 1 was encapsulated by conventional techniques into capsules resistant to gastric juices. Each capsule contained Active material 51.53 Talc 123.47

Lacquer 15:00

I claim: 0 The bismuth iodide complex of the hydroiodic acid addition salt of racemic Z-dehydroemetine.

References Cited by the Examiner UNITED STATES PATENTS 2,513,793 7/ 1950 Frommel 260-270 2,970,999 2/ 1961 Rudner 260-270 3,121,720 2/1964 Barton et a1. 260-288 DONALD G. DAUS, Assistant Examiner. 

